Changes in phrenic nerve compound muscle action potential in streptozotocin-induced diabetic rats

Abstract

PurposeTo evaluate the phrenic nerve compound muscle action potential (CMAP) in rats after diabetes mellitus (DM) induction. MethodsTwenty DM animals (intravenous streptozotocin, 45 mg.kg−1) and 25 controls underwent CMAP analysis before and 30, 60 and 90 days after DM induction. ResultsAmplitude (mV) progressively declined in DM group after 30 (Mean difference (MD): –0.915, 95 % Confidence interval (CI) –1.580 to –0.250, p < 0.01), 60 (MD: –1.122, 95 % CI –1.664 to –0.581, p < 0.001) and 90 days (MD: –2.226, 95 % CI –3.059 to –1.393, p < 0.001); as well as the area (mV.ms) after 30 (MD: –3.19, 95 % CI –5.94 to –0.44, p < 0.05), 60 (MD: –3.94, 95 % CI –6.24 to –1.64, p < 0.001) and 90 days (MD: –8.64, 95 % CI –12.08 to –5.21, p < 0.001). Transient differences were observed in latency and duration at 60 days. ConclusionsThe progressive changes in phrenic nerve CMAP observed during DM suggest a decrement in axonal function rather than substantial demyelination.